So far, there is no regulation anywhere in the world specific to the environmental impact of software – a fact that runs alongside the reality that neither consumers nor investors are towards or away from companies based on the green credentials of their software.  

Many experts expect Europe to be the first region to enact regulation that enforces green software practices. One of them is Santiago Fontanarrosa, vice-president of technology at Globant, a digital services company and author of the book Green software engineering: exploring green technology for sustainable IT solutions.

According to Fontanarrosa, Europe is well-positioned to lead in green software regulation thanks in part to its strong sustainability initiatives and advancements in software engineering. Europe is commitment to sustainability, as demonstrated by ambitious initiatives like the European Green Deal. Moreover, France leads in green software research, and Germany’s Blue Angels offers the first global eco-friendly software certification.  

Fontanarrosa said green software is not only about applying certain development practices, it’s also about how to deploy and use the resulting applications. As for what developers can do, many of the green software techniques can be taken from the practices used by people who wrote programs in the 1970s, when CPUs were much less powerful, and memory and storage were much more limited. As processors became faster and memory and storage grew, software engineers have become more complacent. 

“Today, my iPhone has more computing power than the machine I used when I started working in the 1990s,” says Fontanarrosa. “I have seen a big change since I began my career. Developers have become less concerned about how they use resources, like CPU and memory. And they no longer apply optimisation techniques. For example, when you have an algorithm that does a loop to go through a very long list, they don’t look for ways of making that part of their code more efficient.”  

When it comes to green software, efficiency pertains to how much energy a program consumes to perform its functions. This involves optimising not only the use of CPU time, memory access and I/O, but also the transfer of data over networks. If coders simply thought more about the physical operations going on underneath their code, they would develop greener software. 

For example, as compared to a program that periodically checks for updates, an event-based architecture that reacts only when new data becomes available is more efficient because it reduces the number of network requests. Bigger design decisions are also important – an architect can take into account the fact that energy is cleaner at certain times of the day, and decide to have certain intensive tasks performed during those optimal periods.  

As for deploying software, one of the underlying principles is to minimise the amount of data traveling around networks, while another is to be selective of datacentres. 

“The cloud nowadays is a commodity everyone uses,” says Fontanarrosa. “But the cloud is actually a big datacentre somewhere that consumes a lot of energy. If I can choose a data provider cloud that uses more green energy, that will have a big impact on my carbon footprint.” 

Fontanarrosa also advises developers and operators to reduce the number of instances they’re using on the cloud. “Nowadays, you have a credit card, you do two clicks, and you have a whole new infrastructure up there,” he says. “You don’t even worry about it. That’s the kind of mentality that we need to start changing.” 

One example that illustrates how much of an impact software can have is given by Dutch software guru Danny van Kooten in a 2020 blog post that influenced many other developers to make similar changes.

Van Kooten estimates that he reduced emissions by 59,000 kg of CO₂ per month by making a very small change to his WordPress plugins that run on more than two million websites. That savings is the amount of CO₂ used to fly from Amsterdam to New York five times. He says that assuming the average website receives about 10,000 visitors a month and uses cache to serve returning users, a monthly savings of 10,000 kWh can be achieved for every 1 kilobyte a programmer shaves off of their JavaScript.

Another example is described in Fontanarrosa’s book, where he compares two implementations of the Fibonacci sequence, using the CodeCarbon tool to measure energy consumption. The first implementation used a recursive implementation and the second used an iterative approach with a for-loop. The iterative implementation used 99.34% less energy and reduced CO₂ emissions by 99.35%. 

“This striking difference demonstrates how thoughtful implementation choices in algorithm design can drastically reduce energy consumption and emissions, showcasing the potential for greener and more efficient software development,” says Fontanarrosa. 

Fontanarrosa says that even if governments are not pushing for green software, businesses and consumers can make it a reality. One encouraging sign is that a lot of companies have joined the Green Software Foundation since its inception in May 2021, including Fontanarrosa’s organisation, Globant. 

The mission of the Green Software Foundation – which was founded by Accenture, GitHub, Microsoft and ThoughtWorks – is to “build a trusted ecosystem of people, standards, tooling and best practices for green software”.

According to Green Software Foundation, the ICT sector will account for 14% of the world’s carbon footprint by 2040, most of which will be from smartphones and datacentres. The website says that software developers contribute to global emissions in many ways. One is by producing new versions of their products, which often requires better hardware to run, rendering the existing computers obsolete.  

One encouraging sign of progress is that the Green Software Foundation’s Software Carbon Intensity (SCI) specification recently achieved ISO standard status. However, this is nothing like government-backed regulation as SCI is still a voluntary, industry-driven standard. 

“I encourage everyone to learn about green software,” says Fontanarrosa. “Go to the Green Software Foundation webpage, or any other related resource, to start thinking about it and trying to introduce minor changes in your digital products. Minor changes sum up to a big impact.” 

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